zuì hǎo
你最好早点儿出发
nǐ zuì hǎo zǎo diǎnr chū fā
You'd better leave earlier.
这件事你最好事先通知他一声。
Zhè jiàn shì nǐ zuì hǎo shì xiān tōng zhī tā yī shēng.
You'd better notify him about this matter in advance.